Assessing Ionospheric Convection Estimates From Coherent Scatter From the Radio Aurora

Abstract

Coherent radar backscatter spectra from auroral E region plasma irregularities can be measured with great precision and accuracy. The Doppler spectra obtained from those measurements can be used to estimate auroral convection patterns using an empirical model. These estimates are consistent with rocket, optical, and incoherent scatter radar data, but direct comparison between the different data sets is not straightforward. In order to establish the quality of the empirical model, alternative approaches are then needed. In this work, we use the electrostatic nature of the convection electric field to assess the physical consistency of the empirical model: The model will be satisfactory to the extent that the convection patterns derived from them are incompressible. The incompressibility criteria were assessed for the estimated convection patterns obtained from the substorm of 20 December 2015. Two different approaches were used for this assessment. First, an electrostatic potential was fitted to the convection pattern produced by the empirical model. A good fit implies that there exists an incompressible convection pattern consistent with the Doppler spectra measurements. Second, the uncertainties on the Doppler spectral estimates where propagated through the empirical model to calculate the expected uncertainties on the divergence of the convection field obtained directly from the empirical model. The convection field will be incompressible if its divergence lies within the uncertainty estimates. Both approaches indicate that the evaluated convection patterns are consistently incompressible.

The Future of Auroral E-region Plasma Turbulence Research

“…Further work on deriving the ionospheric convection electric field from E-region coherent scatter has been performed by Rojas et al (2018) to determine the validity of using the E-region coherent scatter measurements as a means to derive the ionospheric convection pattern. This work shows the potential for operational measurements of scall-scale E-region electric fields during active conditions using a distributed network of E-region coherent scatter radars.…”

The future of auroral E-region plasma turbulence research

“…Further work on deriving the ionospheric convection electric field from E-region coherent scatter has been performed by Rojas et al (2018) to determine the validity of using the Eregion coherent scatter measurements as a means to derive the 10.3389/fspas.2022.1062358 ionospheric convection pattern. This work shows the potential for operational measurements of small-scale E-region electric fields during active conditions using a distributed network of E-region coherent scatter radars.…”

“…FIGURE 7 (A) The magnitude of the plasma density perturbations based on the phase velocity of the perturbations and the flow angle with respect to E×B for k = 3 m −1 (B) Empirical model determination of the Doppler spectra characteristics using the model proposed by Bahcivan (2007) compared with the Doppler spectra numerically determined from the fluid model of Rojas Villalba et al (2022). In the figure, 'sim' refers to the simulated values, "ext" refers to extended values calculated from the simulation using the symmetry properties of the Fourier transform, and "fit" refers to values that were derived from an empirical model described inRojas et al (2018).Figure from Rojas Villalba et al (2022).…”

Hybrid Plasma Simulations of Farley‐Buneman Instabilities in the Auroral E‐Region

“…Although linear fluid theory predicts incorrectly the rapid growth of very short wavelengths, linear kinetic theory shows that ion Landau damping effectively suppresses this growth (Schmidt & Gary, 1973). Using these linear approximations, empirical models have been developed to interpret coherent radar backscatter and estimate local convection fields (Rojas et al., 2018). Nevertheless, linear theory falls short in explaining several features observed in the experimental data (Oppenheim et al., 1996).…”

“…empirical models have been developed to interpret coherent radar backscatter and estimate local convection fields (Rojas et al, 2018). Nevertheless, linear theory falls short in explaining several features observed in the experimental data (Oppenheim et al, 1996).…”